Primary production and existing amount of herbaceous biomass

Existing biomass of tropical savanna is lower than that of tropical rainforest. The primary production of the tropical savanna, which has rich rhizosphere and the grasses vigorously grow under heavy grazing of animals, is similar to that of tropical rainforest, whose rhizosphere is shallow, of poor quality. As such, tropical savanna greatly contributes to the reduction of CO2 when compared to tropical rainforest1. As advancements in fermentation and gasification techniques, the utilization of herbaceous biomass as a biofuel, has attracted much attention. Annual production of herbaceous by-products is estimated at 18.95 million tons (Mt) from rice straw and husks, 1.90 Mt from barley and wheat, 0.5 Mt from sugarcane. Furthermore, estimated data of forage production of 40 t/ha in 560,000 ha of abandoned fields, 40 t/ha in 79,000 ha of abandoned paddy field, 5-20 t/ha in un-utilized land comes to 32.08 Mt. The total of available herbaceous biomass comes at least to 53.43 Mt/year in Jpan. But these are utilized partly for forages of cattle now.